Activity 4.6

Activity . Teacher’s demonstration – Drop a small piece of sodium, about the size of a couple of grains of rice, into ethanol (absolute alcohol). What do you observe? How will you test the gas evolved? 2Na + 2CH CH OH → 2CH CH O – Na + + H (Sodium ethoxide) Alcohols react with sodium leading to the evolution of hydrogen. With ethanol, the other product is sodium ethoxide. Can you recall which other substances produce hydrogen on reacting with metals? Reaction to give unsaturated hydrocarbon: Heating ethanol at K with excess concentrated sulphuric acid results in the dehydration of ethanol to give ethene – CH CH OH CH = CH + H O Hot Conc. H SO −  →  The concentrated sulphuric acid can be regarded as a dehydrating agent which removes water from ethanol. How do alcohols affect living beings? When large quantities of ethanol are consumed, it tends to slow metabolic processes and to depress the central nervous system. This results in lack of coordination, mental confusion, drowsiness, lowering of the normal inhibitions, and finally stupor. The individual may feel relaxed without realising that his sense of judgement, sense of timing, and muscular coordination have been seriously impaired. Unlike ethanol, intake of methanol in very small quantities can cause death. Methanol is oxidised to methanal in the liver. Methanal reacts rapidly with the components of cells. It coagulates the protoplasm, in much the same way an egg is coagulated by cooking. Methanol also affects the optic nerve, causing blindness. Ethanol is an important industrial solvent. To prevent the misuse of ethanol produced for industrial use, it is made unfit for drinking by adding poisonous substances like methanol to it. Dyes are also added to colour the alcohol blue so that it can be identified easily. This is called denatured alcohol.